Refs #14131 -- Documented why paginating large QuerySets may be slow.

    clause or with a default :attr:`~django.db.models.Options.ordering` on the

    model.

    .. note::

    .. admonition:: Performance issues paginating large ``QuerySet``\s

        If you are using a ``QuerySet`` with a very large number of items,

        requesting high page numbers might be slow on some database backends.

        If you're using a ``QuerySet`` with a very large number of items,

        requesting high page numbers might be slow on some databases, because

        the resulting ``LIMIT``/``OFFSET`` query needs to count the number of

        ``OFFSET`` records which takes longer as the page number gets higher.

``per_page``

    The maximum number of items to include on a page, not including orphans